The subject invention relates to optical tables, and particularly to honeycomb tabletops for optical tables.
Honeycomb tabletops are typically used for supporting and positioning highly sensitive scientific equipment such as optical devices. The tabletop generally includes an upper layer, a lower layer and a honeycomb core. The upper layer is typically provided with a plurality of tapped holes which are used for securing equipment to the tabletop surface. The honeycomb core maintains the structural rigidity and flatness of the upper layer, despite the numerous holes drilled therein. In the past, granite plates and slabs were often used in this setting. However, due to the great weight of the slabs and the difficulty in securing components to such surfaces, honeycomb tabletops have grown increasingly popular.
Unfortunately, existing honeycomb tabletops are not without their drawbacks. Specifically, the tapped holes provide openings through which liquid or other debris spilled upon the table surface may pass into the interior. Due to the depth of the tabletop, such spills are difficult or impractical to clean.
A number of attempts have been made to develop a design to address these problems. Specifically, U.S. Pat. No. 4,621,006 to Terry, et al. discloses a tabletop design in which an intermediate sheet is positioned between a relatively deep honeycomb core portion adjoining the lower layer of the table and a relatively thin honeycomb portion adjoining the upper layer. Terry teaches that the longer cells of the lower honeycomb section are completely sealed off so that only the shallow cells of the smaller honeycomb section need be cleaned.
U.S. Pat. No. 4,645,171 to Heide discloses a honeycomb tabletop in which "cavity enclosures" are secured, such as by welding, to the interior surface of the upper layer, apparently coaxially aligned with the holes of the upper layer. The holes and enclosures are then positioned with respect to the honeycomb core such that the enclosures are situated substantially within the middle of the honeycomb cells. Heidi teaches that the enclosures have a closed bottom portion which prevents any liquid or other contaminant from entering the interior portion of the table, and that the table may be cleaned by "simply wiping the table surface clean and applying suction to remove the spillage from the cavities." In contrast, U.S. Pat. No. 4,853,065 discloses the use of a sealing sheet that incorporates rows and columns of projections which may be aligned with the internal cells of a table's honeycomb core to provide a means of sealing the holes of the upper layer from the honeycomb core.
Yet another honeycomb tabletop design is disclosed in French Patent No. 2,519,270, in which a series of sleeves are positioned coaxially aligned beneath each of the individual holes of the upper layer. The bottom portion of these sleeves rests upon an interconnecting plate, which in turn rests upon a honeycomb stiffening structure, which in turn rests upon a lower layer. The sleeves prevent the honeycomb stiffening structure from coming into contact with objects, dust or liquids accidentally entering through holes of the upper layer.